Piston



QNO Model.)

H. H. MERRILL.

PISTON.

No. 560,004. Patented May 12, 1896.

Ins/67022712- UNITED STATI-3s IPATENT OFFICE.

IIATTIE II. MERRILL, OF CHICAGO, ILLINOIS.

PISTON.

SPECIFICATION forming part of Letters Patent No. 560,004, dated May 12, 1896.

Application filed November 4, 1895. Serial No. 567,819. (No model.)

To @ZZ whom t may concern:

le it known that I, Herrin H. MERRILL, of Chicago, in the county of Oook and State of Illinois, have invented certain new and useful Improvements in Pistons 3 and I do hereby declare that the following is a full, clear, and exact description thereof, reference bein ghad to the accompanying drawings, and to the letters of reference marked thereon, which form a part of this specification.

rIhis invention relates to improvements in pistons, and refers more specifically to an improved form and arrangement of the packing devices of pistons subject to the pressure of liquids or gases.

The object of the invention is to providea piston of simple construction in which the packing-leather is arranged in such a manner as to prolong its Working lite and to retain its full effectiveness until entirelyT worn out, the invention having also in view the production of a piston which will not become inoperative, or partially so, by reason of the packing-leather becoming stuck fast to its support from the piston remaining unused for a long period ot' time, or from any other cause.

The invention consists in the matters hereinafter described, and more particularly pointed out in the appended claims, and the same will be more readily understood by reference to the accompanying drawings, in Whieh- Figure l is a side elevation of a piston embodying my invention. Fig. 2 is an axial section of the same. Fig. 3 is a bottom end view. Fig. 4 is a side View of the inner packing-support. Fig. 5 is a top plan view of the outer packing-support. Figs. 6 and '7 are views similar to Figs. and el., respectively, showing a modiiication.

Referring to said drawings, A designates a piston rod having its end portion screwthreaded, as at a.

I3 designates a packing-supporting disk or ring screw-threaded to lit upon the piston-rod A, having at one side a smooth annular face b and provided at its opposite side with an integral nut B', by means ot which the ring may be turned upon or removed from the piston-rod A. rlhe exterior diameter of said disk l is slightly less than the interior dithe leather-packing cup C and hold the latter outward in contact with the interior of the cylinder, the exterior or peripheral surface d of said packing-support being cylindrical and arranged to extend parallel with the wall of the cylinder and being of a width equal to the depth of the cup-leather O. lVithin said peripheral surface d are formed a plurality of channels d d', placed at uniform intervals around said inner packingsupport and extending inwardly from the outer end thereof toward the bottom of the cup-leather C. These channels are made tapering or of gradually-diminishing capacity from their outer ends toward the bottom of the cup-leather, as indicated clearly in Fig. 4, being conveniently and as herein shownv made in the form of concave or rounded grooves relatively wide at their outer ends and tapering uniformly to the outer surface of the support at the base of the cup-leather. Said grooves or channels fl/ are so spaced as to leave intervening portions d2 d2 between each pair of grooves, which portions d2 serve to support the packing-leather throughout the full lengt-h of its cylindric portion. support D is provided with suitable means for turning it upon the piston-rod, herein shown as in the form of an integra-l nut portion D, adapted to be engaged by any ordinary wrench, whereby the said part may be turned up to clamp the cup-leather between its inner face and the outer packing-support D.

The construction described, in which the cup-leather is both supported and subjected to internal pressure throughout its full depth, is a novel one and productive of new and beneficial results. The pressure of the liquid is transmitted through said channels to the interior of the cup-leather throughout the full depth of the latter, thus insuring a close and The ICO

perfect packing and distributing the wear over the entire outer surface of the leather. This internal pressure is, however, by reason of the tapered form of the pressure-channels, operative over a greater area of the leather at the margin of the packing, and consequently said margin will be pressed outward more forcibly and will wear away faster than the remainder of the leather. By reason of said tapered form or gradually-diminishing capacity of the channels this relativelyT greater pressure at the margin of the packing-leather will be maintained as the latter wears down throughout the entire working life of the packing.

Another and important advantage obtained by carrying the channels to the full depth of the packing-cup is that the packing is thereby expanded at all parts, and thus maintained fully operative throughout its entire depth, whether the piston be used daily or only occasionally at long intervals apart, whereas, in the constructions ordinarily employed, it has been found that the rusting or oxidizing action of the water upon the metal packing-supports and the tendency of the leather to become sticky, when long submerged in liquid, cause the packing to stick fast to said supports wherever it lies in contact with the latter and is not subjected to a direct separating pressure', and thus renders the piston defective long before the packing is otherwise worn out. This objection is entirely obviated by the construction described.

IV am aware that it is not broadly new to subject the interior of a packing-leather to pressure by means of passages formed in the inner packing-support especially provided for this purpose, such provision being shown in the patent to Collyer, No. 236,087, dated January 25, lSSl, and also in the patent to Baldwin, No. 220,784, dated October 2l, 1879'. l am not aware, however, that a 'construction has everbefore been devised wherein a packing-leather having a cylindrical side portion adapted to restI in working contact with the interior of the cylinder has been subjected to pressure throughout substantially the full depth or width of said cylindrical side portion by means of channels arranged in the manner shown, nor a construction wherein the area of pressure upon the interior of the packing-leather is gradually diminished from its outer margin inwardly throughout its depth.

In Figs. 6 and 7 I have shown a modification in which the pressure-channels cl3 are of uniform capacity throughout their entire depth and are separated by relatively narrow ribs d4. This construction, while not in all respects as desirable as that shown in the previously-described iigures, is nevertheless an improvement in the art, and obviouslypossesses most of the advantages attained by said prior construction.

It is to be particularly noted that in each of the forms described the construction is such that a piston embodying my invention may be made at as low a cost as can one of the ordinary construction, while its durability is very considerably increased.

l claim as my inventionl. In a piston the combination of a cupshaped packing-leather adapted to rest with its side surface in contact with the interior of the cylinder, an exterior supporting-ring against which the base of the cup-shaped packing-leather rests, and an inner packingsupport connected at its base with the outer support, the periphcryof said inner packingsupport being in contact with and constructed to support the packing-leather throughout substantially the full depth of the latter and being provided with pressure-channels at intervals around said periphery and extending substantially the full depth of the cup-leather, substantially as described.

2. In a piston, the combination of a cupshaped packing-leather having' a cylindrical side adapted to itagainst the interior of the cylinder, an outer packing-support against which the base of the cup-leather is secured, and an inner packing-support having a cylindrical periphery adapted to fit within and support the cup-leather throughout its fullV depth, the periphery of said inner support being provided with pressure-channels at uniform intervals around said periphery and extending from the outer margin of the support inwardly the full depth of the cup and of gradually-diminishing width from said outer margin inwardly7 substantially as dcscribed.

IOO

In testimony that ly claim the foregoing as IOS 

